linux-kernel - [PATCH 00/11] sched/wait: Replace wait_on_atomic_t() with wait_var

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Date:   Thu, 15 Mar 2018 13:19:02 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org
Cc:     Dan Williams <dan.j.williams@...el.com>,
        David Howells <dhowells@...hat.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Stanimir Varbanov <stanimir.varbanov@...aro.org>,
        Chris Mason <clm@...com>,
        Anna Schumaker <anna.schumaker@...app.com>,
        Joel Becker <jlbec@...lplan.org>,
        James Hogan <jhogan@...nel.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        George Spelvin <linux@...encehorizons.net>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>
Subject: [PATCH 00/11] sched/wait: Replace wait_on_atomic_t() with wait_var_event()

I never really liked the whole wait_on_atomic_t() because of the hard-coded
type and condition. And when Dan proposed to add 50+ lines of duplication to
implement wait_on_atomic_one() I figured that was it.

Instead implement wait_var_event(), which at the fundamental level is much the
same hashed-waitqueue as wait_on_atomic_t() is, but it doesn't care about the
type or condition.

It is further modelled on the existing wait_event() API and is otherwise
consistent with that.

The existing:

  wait_for_atomic_t(&my_atomic, wait_atomic_t, TASK_UNINTERRUPTIBLE);
  wake_up_atomic_t(&my_atomic);

can be replaced with:

  wait_var_event(&my_atomic, !atomic_read(&my_atomic));
  wake_up_var(&my_atomic);

And Dan can do what he needs done using:

  wait_var_event(&my_atomic, atomic_read(&my_atomic) == 1);


---
 arch/mips/kernel/process.c                         |   2 +
 arch/mips/kernel/traps.c                           |   4 +-
 drivers/gpu/drm/drm_dp_aux_dev.c                   |  13 +--
 drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c |  14 +--
 drivers/media/platform/qcom/venus/hfi.c            |   8 +-
 fs/afs/cell.c                                      |   6 +-
 fs/afs/rxrpc.c                                     |   6 +-
 fs/afs/server.c                                    |   6 +-
 fs/btrfs/extent-tree.c                             |  14 ++-
 fs/btrfs/ioctl.c                                   |   2 +-
 fs/fscache/cookie.c                                |   7 +-
 fs/nfs/inode.c                                     |   5 -
 fs/nfs/pagelist.c                                  |   6 +-
 fs/nfs/pnfs_nfs.c                                  |   2 +-
 fs/nfs/write.c                                     |   6 +-
 fs/ocfs2/filecheck.c                               |   9 +-
 include/linux/fscache-cache.h                      |   2 +-
 include/linux/wait_bit.h                           |  95 +++++++++++++-----
 kernel/sched/wait_bit.c                            | 110 +++++----------------
 19 files changed, 147 insertions(+), 170 deletions(-)